In animation and effects products, transformation hierarchies are built using a dedicated user interface, which is typically called a schematic view. A transformation hierarchy specifies, for example, three-dimensional transformations that are concatenated according to the relationships in the tree. In a schematic view, sets of objects are “constrained” to another object by specifying a parent-child relationship between them. These transformations may be used, for example, to perform effects on image sequences. A digital video effect (DVE) is an example of an operator that can use a specific transformation from the schematic view to render a set of images. DVE operators are manipulated in another user interface that defines an image data flow of effects processing, such as an effects tree. The data flow user interface shows a graph of image effect nodes, including the DVE operator that renders the images based on the transformation specified in the schematic view. This schematic view typically is shown separately from any data flow user interface.
There are two primary problems that users face when using schematic views and effects trees. First, the two views are not in context. The user needs to keep a visual association between the transformation nodes in the schematic view and the image-rendering objects that are affected by them. Second, the hierarchy shown in the typical schematic views follows a tree structure, which enforces a parent-child relationship. A parent can have multiple children, but a child cannot have multiple parents. In mathematical terms, this relationship implies that the parent provides a post-transform matrix to a child matrix. However, this data structure or user interface is not amenable to providing a single pre-transform matrix to multiple objects.